Infections with Baylisascaris procyonis in humans and raccoons

Baylisascaris procyonis is an ascarid which parasitizes the small intestine of raccoons. The parasite is not very pathogenic in the raccoon because larvae do not migrate in this host. In other animals the larvae migrate through the body. They do not develop into adult worms in the intestine but rather become encysted in granulomas, showing a preference for the brain. In humans these larvae cause different larva migrans syndromes. Patients with neural larva migrans syndrome show severe brain symptoms and the disease is sometimes fatal. This article describes the life cycle of the worm and the incidence, symptoms, diagnosis, treatment, and prevention of larva migrans syndromes, paying special attention to the Dutch situation.     

Persistent cutaneous larva migrans due to Ancylostoma species

Cutaneous larva migrans is considered to be a self-limited parasitic infection of about 2 to 8 weeks' duration, though it has been reported to persist for as long as 55 weeks. In this case, a healthy 47-year-old white man had multiple serpiginous lesions typical of cutaneous larva migrans for 18 months. A biopsy taken 2 months before presentation showed a parasite consistent with Ancylostoma species deep in a hair follicle. The patient initially responded to topical thiabendazole, but relapse occurred when therapy was discontinued. Oral thiabendazole cured the problem after 22 months of infestation. Cutaneous larva migrans may sometimes be long-standing, here almost 2 years, even in a healthy patient. Organisms may reside deep in the hair follicles. Topical thiabendazole may not penetrate to this depth, necessitating oral thiabendazole therapy.     

Hepatic Toxocara infestation

We describe the case of a patient with infestation of the liver by visceral larva migrans as the sole manifestation of the disease. The difficulties in the diagnosis if no other organs are affected is stressed. The diagnosis is made by ultrasound and CAT scan and serological tests by ELISA. Tiabendazol is the treatment of choice.     

Visceral larva migrans infections caused by toxocara species (author's transl)

A total of 4656 serum samples from suspect persons were investigated for Toxocara antibodies over the last 10 years. Using the Ouchterlony technique antibodies were demonstrated in 707 cases, and in 409 cases with the help of the microprecipitation test using secondary larvae. It was shown that the living larva test is highly specific and very sensitive so that a positive reaction can be taken as definite evidence of infection. Clinical symptoms were characterised by high eosinophilia, ophthalmologic changes, lung involvement, central nervous affection and increase of gamma-globulins. A history of contact with dogs or cats was an additional indicator. Treatment of larva migrans syndrome has to date remained unsatisfactory as no effective and well tolerated drug is known.     

Toxocara infestations in humans: symptomatic course of toxocarosis correlates significantly with levels of IgE/anti-IgE immune complexes

Infestations of humans with the parasitic nematode T. canis are common in both developing and industrialized countries. Most infestations induce a clinically inapparent course of infection, however, severe clinical manifestations, i.e. visceral larva migrans (VLM) or ocular larva migrans (OLM) syndromes are observed. To find an explanation for the different courses of toxocarosis we examined several serological parameters: the expression of (i) specific IgE (Immunoblot, IB), (ii) specific IgG subclasses (IgG1-4, ELISA and the formation of (iii) IgE/anti-IgE immune complexes. Serum samples were obtained from persons with symptomatic (VLM, OLM) and asymptomatic course (AS) of the infestation. As antigen, T. canis excretory/secretory (TES) antigen from L3 larvae was used. Reactivity of IgE against SDS-PAGE separated TES antigens was marginally higher in toxocarosis patients (35%) than in asymptomatics (24%), but without statistical significance. TES-specific IgG (1-4), predominant subclass in all three groups was IgG1, followed by IgG2, IgG4 and IgG3. Subclass IgG1, 2, 4 showed significant differences between patients with VLM associated symptoms and asymptomatic persons (P < 0.001) but not between patients with OLM associated symptoms and asymptomatics. Significantly elevated levels of IgE/anti-IgE immune complexes were detected in sera of patients with symptomatic course of the disease, both VLM and OLM (P < 0.001). Whereas specific IgG may act via antibody dependent cell-mediated cytotoxicity mechanisms, IgE/anti-IgE immune complexes might possibly participate in VLM and OLM by inducing type III hypersensitivity.     

Visceral larva migrans and the hypereosinophilia syndrome

This is a case of visceral larva migrans and hypereosinophilia syndrome with persistently elevated white blood cell count despite adequate medical therapy in a 4-year-old boy with leukocytosis and splenomegaly. Medical history included reactive airway disease and geophagia (pica). Serology for Toxocara canis revealed elevated IgG and IgM titers. Ophthalmologic evaluation ruled out ocular larva migrans. After 5 days of thiabendazole therapy, leukocytosis persisted, and a second course of anthelmintics was prescribed. Two weeks later, a decrease in leukocytosis was noted. Thiabendazole therapy was continued for 15 more days. Repeated serology for T canis revealed a decreased IgM titer and a further elevated IgG titer. Follow-up showed increased physical activity, improved respiratory status, and resolution of splenomegaly.     

Larva migrans

In cases with characteristic case history (contact with tropical sandy beaches and other sandy, warm and moist regions) and typical clinical picture (itching cordlike lesions) larva migrans infection should be considered. This case report is given because of the growing number of tourists visiting these countries and the not general known treatment.     

A comparison of the effect of two regimens of infestation on the development of resistance by cattle to the cattle tick, Boophilus microplus (Can.)

The development of resistance to Boophilus microplus by cattle was studied using sets of cattle twins, in stalls. One twin from each set received 3 infestations of 40,000 larvae and the other a continuous infestation of 1,000 larvae a day over the same period. Sets of twins were then challenged with 1,000 larvae a day for 40 days and 2 field infestations of 20,000 larvae. Correlations of ranking for resistance made at 40-day periods during daily infestations of 1,000 larval ticks or for corresponding intermittent infestations of 40,000 larvae were low until animals had received 120,000 larvae. Thereafter irrespective of method of infestation correlations of ranking were relatively high (r = 0.61-0.96) between periods of infestations or method of infestation including 2 field infestations. Fewer adult female ticks matured on the daily infested animals than on the intermittently infested animals during the treatment period, but animals developed a similar resistance level whether infested with either technique.     

Toxocariasis and functional intestinal disorders. Presentation of 4 cases]

We report 4 cases of adults patients, suffering from irritable bowel syndrome, which had been attributed late to toxocariasis and for whom the treatment led to recovery. Hypereosinophilia was present only in 3 cases. These cases show that toxocariasis is not limited anymore to its two classical expressions: visceral larva migrans and ocular toxocariasis. So it is useful to think of it to confirm and treat it in the case of patients suffering from irritable bowel syndrome. This enables shorter diagnosis delay (14 months in average for our patients) and this is essential for therapeutic efficiency.     

Determination of suramin by micellar electrokinetic chromatography with direct serum injection

Visceral larva migrans (VLM) is a clinical syndrome caused by infection of man by Toxocara spp, the common roundworm of dogs and cats. Tissue migration of larval stages causes illness specially in children. Because larvae are difficult to detect in tissues, diagnosis is mostly based on serology. After the introduction of the enzyme-linked immunosorbent assay (ELISA) using the larval excretory-secretory antigen of T. canis (TES), the diagnosis specificity was greatly improved although cross-reactivity with other helminths are still being reported. In Brazil, diagnosis is routinely made after absorption of serum samples with Ascaris suum antigens, a nematode antigenically related with Ascaris lumbricoides which is a common intestinal nematode of children. In order to identify T. canis antigens that cross react to A. suum antigens we analyzed TES antigen by SDS-PAGE and Western blotting techniques. When we used serum samples from patients suspected of VLM and positive result by ELISA as well as a reference serum sample numerous bands were seen (molecular weight of 210-200 kDa, 116-97 kDa, 55-50 kDa and 35-29 kDa). Among these there is at least one band with molecular weight around 55-66 kDa that seem to be responsible for the cross-reactivity between T. canis and A. suum once it disappears when previous absorption of serum samples with A. suum antigens is performed.     

Diagnosis and management of parasitic hypereosinophilia]

ETIOLOGY: Helminth infestation of the digestive tract or organ tissues is a common and curable cause of high eosinophil counts. Parasite infestation should be the number one suspect in patients with hypereosinophilia. DIAGNOSIS: Clinical signs and epidemiology are suggestive. If the patient has travelled to the tropics, one should consider both exotic and cosmopolite parasites. LABORATORY TESTS: The causal agent can sometimes be identified by direct examination of tissue samples, depending on the localization. In practice however identification may be a difficult task when the level of infestation is low or the helminth is in a larval stage. The epidemiological situation, clinical features and results of serology tests must all be considered for diagnosis. ANTIHELMINTH TREATMENT (TEST): Clinical improvement after treatment can be a criteria for positive diagnosis. Normal eosinophil counts followed later by normal serology confirms the diagnosis.     

Involvement of serotonergic receptor subtypes in the production of antinociception by psychological stress in mice

The infestation of birds by immature Ixodes ricinus was studied during 6 months in a Swiss woodland, where Lyme borreliosis is endemic. Thirteen passerine species were found to be parasitized by I. ricinus subadults and specially Turdus merula, T. philomelos and Erithacus rubecula. Overall, 300 larvae and 162 nymphs were collected on 95 avian hosts. Prevalence of infestation of nymphs on birds was higher in spring; larvae peaked in summer. The infection of birds by Borrelia burgdorferi was also studied using blood cultivation and examination of ticks. Motionless spirochetes were isolated from two E. rubecula. Infected ticks were removed from five species of passerines, and mainly three species of Turdidae (T. merula, T. philomelos and E. rubecula). Infection rate of larvae and nymphs by spirochetes averaged 16.3% and 21.7%, respectively. These percentages, compared to the infection rate of questing ticks collected through dragging, suggest that some Turdidae may play a role as amplifying hosts for spirochetes in the focus.     

Effects of cattle tick (Boophilus microplus) infestation on the bovine immune system

The immunosuppressive effect of experimental Boophilus microplus infestation on bovine peripheral blood lymphocytes (PBL) and on host antibody production to a protein antigen (ovalbumin) was examined. Boophilus microplus infestation caused a marginal decrease in the percentage of T lymphocytes in PBL, which was observed in both lightly (5000 larvae) and heavily (40,000 larvae) infested cattle, and began at the second infestation and continued until the end of the fourth infestation. The percentage of B lymphocytes in heavily tick-infested cattle was less than that in non-infested control cattle after the fourth infestation. The response of PBL from tick-infested cattle to phytohemagglutinin (PHA) was always less than that of tick-free cattle after the second infestation. No noteworthy differences were detected between the three stages of tick infestation, that is, 1 week before the peak of adult engorgement, the middle of the peak and 1 week after all ticks had dropped. Boophilus microplus saliva (100 microliters ml-1) suppressed 47% of the response of bovine PBL to PHA in vitro. This suppressive effect of saliva may contribute to the lower responsiveness of PBL from tick-infested cattle. Antibody production by tick-infested cattle was examined during the third and fourth heavy tick infestation. Tick-infested cattle showed a diminished response against ovalbumin after the second immunization. The immunosuppressive effects of tick infestation may play an important role in tick survival or in the transmission of tick-borne diseases in the field.     

Myiasis caused by Dermatobia hominis

In two patients, a woman of 35 and a man of 62 years old, myiasis caused by the larvae of the fly Dermatobia hominis was diagnosed. Both patients had recently returned from a visit to Central America. This ectoparasitosis is found in Central and South America. Patients present themselves with an insect bite which fails to heal. If the clinical presentation is unknown, the disease may well be mistaken for furunculosis. The condition may be easily treated by applying vaseline to the insect bite, which causes extrusion of the larva.     

Intestinal strongyloidiasis manifesting as eosinophilic pleural effusion

Strongyloidiasis caused by the helminth Strongyloides stercoralis is usually asymptomatic or causes mild dermatologic or gastrointestinal symptoms. In immunocompromised hosts, hyperinfection and dissemination can occur. In this case, I describe a nonimmunocompromised Southeast Asian man who had an eosinophilic pleural effusion, peripheral eosinophilia, and rhabditiform larvae of S stercoralis in the stools. There was complete resolution of the pleural effusion after thiabendazole therapy, thus suggesting strongyloidiasis as the cause of the effusion. Helminthic infections like strongyloidiasis should be considered in the differential diagnosis of an eosinophilic pleural effusion, especially in individuals from endemic areas.     

Toxocara canis: ultrastructural aspects of larval moulting in the maturing eggs

The morphology of the surface of Toxocara canis larvae, developing in the eggs to reach infectivity, has been studied for the first time at an electron microscopical level. In most 11-day and some 15-day eggs, the larvae are surrounded by two shed cuticles. The outer first shed cuticle is composed of two layers. the inner second shed cuticle is much thicker than the outer one. The presence of both shed cuticles indicates that the larva has undergone two developmental stages in the maturing egg. The larvae in most 15-day eggs are surrounded by one shed cuticle composed of outer electron-dense and inner layers. This cuticular sheath is identical with the described inner second shed cuticle, except for its apparently reduced thickness. The infective larvae inside the 30-day eggs are enveloped by one cuticular sheath, derived from the second moulted cuticle, and consisting only of a single layer. The findings are discussed with respect to data concerning the moulting process in other nematode species.     

On-line literature retrieval as a continuing medical education course

The effectiveness of a mass separation technique, previously used for the extraction of larvae of lymphatic-dwelling filarial worms from batches of vector mosquitoes, was tested as a means of recovering infective-stage larvae of Onchocerca volvulus from Simulium ochraceum in Guatemala. Blood-engorged flies, collected from 10 infected human attractants, were maintained for 9 days to allow ingested microfilariae to develop to the infective stage. The numbers of Onchocerca larvae recovered after groups of these flies were crushed and washed into tissue culture fluid in Baermann funnels was compared with the numbers obtained by individual dissections of flies fed on the same subjects. The mass separation procedure gave a mean recovery rate of 0.03 larva/fly and detected larvae only in flies which had fed on those subjects with the highest microfilarial skin densities. Dissections yielded 0.50 larva/fly (a 16.7-fold increase) and detected larvae in flies collected from all test subjects. The explanation for the ineffectiveness of the mass separation technique may lie in the observed sluggishness of infective-stage Onchocerca larvae and a consequent inability to free themselves from the fly fragments in the Baermann funnel.     

A new technique for sacral nerve stimulation: a percutaneous method for urinary incontinence caused by spinal cord injury

We report a 40-year-old Japanese man with a creeping eruption caused by a larva of the nematode suborder Spirurina type X. He had eaten raw small squid (hotaruika) 4 weeks before the serpiginous erythematous eruption appeared on his abdomen. Routine laboratory tests revealed only slight eosinophilia in his peripheral blood. Although we could not find the larva in an excised skin specimen, an indirect immunofluorescence test confirmed the presence of antibodies against larvae of the suborder Spirurina type X. We review 28 reported cases in Japan which showed that creeping eruption caused by larvae of the suborder Spirurina type X has the following clinical characteristics: an incubation time of 1-4 weeks; a migratory, well-defined, narrow, serpiginous erythematous eruption; and only slight peripheral blood eosinophilia. Excision of the advancing end of the track was curative in our patient.     

Two cases of enteric myiasis in man. Pseudomyiasis and true intestinal myiasis

Dipterous larvae were found in the appendices from two postmortem examinations. The single maggot in the first case was not immediately identified in the sections. However, when the posterior end of the larva was recovered from the unsectioned portion of the appendix, it was identified as a maggot of the genus Sarcophaga. The first case was believed to be a case of "pseudomyiasis,+ i.e., the accidental entrapment of a swallowed larva passing through the digestive tract. In the second case, the appendix contained numerous larvae with great variation in sizes and stages of development of the mouth hooks, pharyngeal sclerites, and spiracular breathing plates. Such development was considered to have occurred within the intestinal tract, which indicated that this was a case of true intestinal myiasis.     

Intestinal parasitic infections among rural farming communities in eastern Sierra Leone

A study carried out in four rural, mainly farming villages in the Gorama Chiefdom, Kono District, Eastern Sierra Leone revealed that intestinal helminth infections are prevalent in this area of Sierra Leone. Out of the 1164 persons of all ages who were examined, 853 (73.5%) proved positive for at least one intestinal helminth infection. Ascaris lumbricoides was the most common helminth encountered (37.5%), followed by hookworms, 12.9%; Trichuris trichiura, 12.6%; Schistosoma mansoni, 5.6%; Strongyloides stercoralis, 3.8%; tapeworms 1.0%, and multiple infections were common. Adults used poorly built pit latrines, while children defecated indiscriminately and unsupervised around houses and in the nearby bush. In addition, in most of the villages, domestic water was obtained from polluted streams and rivers. Only one village had protected pipe borne water supply. The high prevalence of intestinal helminth infections in this area results from constant infection and reinfection caused by poor sewage disposal, poor environmental health, and the low socioeconomic status prevailing in these communities.